Device for changing nozzles

ABSTRACT

The invention relates to a device which enables nozzles to be changed without changing the pressure conditions in the container or device associated therewith. According to the invention a connector piece support ( 2 ) is fixed to a pressurised container ( 1 ) wherein a medium ( 20 ) is guided into said container through a nozzle ( 8 ) by means of a lance ( 7 ). Said connector piece is connected to a sealing housing ( 5 ) by means of a locking device ( 3 ) in order to receive the lance ( 7 ). Sealing rings ( 13   a,    13   b,    13   c ) are arranged in the sealing housing ( 5 ) thereby ensuring pressure-tightness in relation to the container ( 1 ) and the surrounding area when the lance ( 7 ) is inserted into the sealing housing ( 5 ).

The invention relates to a device for changing nozzles. In numerousproduction processes spray nozzles are used for various purposes. Thisfunction can be condensation, cooling, cleaning, and vaporizing.According to function, various nozzle types are employed such as fan,hollow cone, or full cone.

As a rule the nozzles are set in the wall of a vessel or a processapparatus. Such mounting facilitates collecting and recirculating theprocess water and also ensures fixed positions for the sprays. Manyprocesses must take place under pressures above or below atmospheric.Thus some medium must be sprayed into pressurized or vacuum vessels orconduits. In addition the vessel or conduit can be single- ordouble-walled and heated or cooled. For continuous operation as a ruleseveral nozzles are provided. These nozzles need to be cleaned andchanged periodically. When one nozzle is being changed at least oneother must be left operational, to avoid changing the nonatmosphericpressure inside the vessel.

Such an applications of this invention is seen in a method of makingpolyethylene enterephthalate (PET). An apparatus using nozzles forcondensing a process liquor and vacuum production by means of multistagesteam injection with upstream spray condensers and downstream mixingcondensers are described in EP 0,244,546. Here glycol is sprayed vianozzles into a subatmospheric-pressure stage.

Systems are known where the nozzles are fixed on a lance, insertedthrough a support tube, and secured in place. Other systems have lancesthat are inserted through a ball valve flanged to the support tube. Inthese systems it is however necessary to stop the process or put up withsubstantial leakage when servicing nozzles.

It is an object of the invention, starting from this state of the art,to provide a device for changing nozzles without having to change thepressure characteristics inside the process vessel or apparatus.

According to the invention this object is achieved in theabove-described apparatus in that a support tube is mounted on thevessel and is connected via a valve with a seal housing for the lanceand that seal rings are provided in the seal housing to ensurepressure-tight sealing between the vessel and its surroundings when thelance is inserted into the seal housing. This device can be used on apressurized or vacuum conduit instead of on a pressurized or vacuumvessel. In addition this device works equally well for cooled or heatedconduits or vessels as well as for single- or multiple-wall conduits orvessels.

Sealing is improved by feeding a blocking liquid into the seal housing.Instead of a liquid it also possible tp urge with gas and achieveadditional sealing.

To ensure near perfect sealing, the blocking fluid is injected betweentwo seals and between the seal assembly and the seal.

The conduits for feeding the blocking fluid in between the seal assemblycan also serve for venting. When horizontal, the entire device ensures acomplete venting of the system. When mounted vertically or at an angle anearly complete venting of the system is possible.

A valve underneath the seal housing serves for draining the sealhousing.

In order to ensure centering of the lance through the seal assembly andto prevent damage to the seals, the lance is centered by at least oneguide in the seal housing. In this manner the nozzle is not damaged whenthe lance engages the flat or tapered seat surface.

Embodiment of the device are described with reference to the drawing.Therein:

FIG. 1 shows the arrangement of a nozzle lance in use;

FIG. 2 shows the intermediate position of the nozzle during installationand removal; and

FIG. 3 shows the outer position of the nozzle during installation andremoval.

FIG. (1) shows a system with a vessel (1) that is above or belowatmospheric pressure and that can be heated or cooled. This vessel (1)carries a support tube (2) that can be oriented horizontally,vertically, or at an angle. The tube has a flat or conically taperedseat surface (2 a) against which a nozzle lance (7) can fit. A flangeconnects the support tube (2) with at least one pressure- orvacuum-tight ball valve (3) and a seal housing (5) so as to be pressure-and vacuum-tight. Other valves with straight-through passages such asfor example slider valves can be used instead of the ball valve. Anozzle lance (7) is fitted to this arrangement, seated in the supporttube (2). A tip of the lance (7) has a spray nozzle (8). The medium (20)to be sprayed in is supplied to the end of the lance (7) by a hose (10).The hose (10) is connected by a snap coupling (9) with the lance (7).The lance (7) is centered by a guide (6) in the tube (2). The sealhousing (5) is directly sealed and flanged with the ball valve (3) andhas at least two seal rings (13 a) and (13 b) that serve to maintainpressure in the vessel (1). A seal ring (13 c) prevents leakage into orfrom the exterior. The seal housing (5) is pressurized with a blockingfluid between the seal rings (13 a, 13 b, and 13 c). This blockingliquid is normally the same as that being sprayed in. The seals (13 a,13 b, and 13 c) can be corrugated or rod seal rings. The blocking liquidis supplied to the seal housing via valves (11 b) from supplies (12 aand 12 b). The seal housing is drained by a lower valve (11 c). The sealhousing is vented during insertion of the lance via the valves (11 a)and (11 b) and the supplies (12 a and (12 b) while feeding in theblocking liquid. In use the lance (7) with ita nozzle (8) is fitted tothe seat (2 a) of the tube (2). In use the medium (20) to be sprayed inis supplied through the hose (10). The valves (11 a and 11 c) areclosed. The ball valve (3) and the valve (11 b) are open. The supplies(12 a and 12 b) are filled with blocking fluid.

To take out the lance (7), feed of the spraying medium (20) is firststopped. The lance (7) is moved into an intermediate position outward ofthe ball valve and adjusted (see FIG. 2). Then the valve (3) is closed.In order to equalize pressure the valve (11 a) is opened. The valve (11b) is closed. The lance (7) is then moved into an outer position (seeFIG. 3) so that the lance tip with the nozzle (8) is inward of the seal(13 c). Then the seal housing (5) is emptied via the valve (11 c). Thelance (7) can then is be pulled completely out.

To insert the lance (7), it is moved into the outer position (see FIG.3) so that the lance tip with the nozzle (8) is inward of the seal (13c). The ball valve (3) and the drain valve (11 c) are closed. A smallamount of the blocking fluid is fed through the lance (7) into the sealhousing. Meanwhile the valves (11 a and 11 b) are open. When the liquidlevels in the supplies (12 a and 12 b) reach predetermined levels, thesupply of the blocking fluid is ended. The seal housing (5) is thusvented of air. The lance (7) is now pushed into the intermediateposition just outward of the ball valve (3) (see FIG. 2). The valve (11a) is closed and the valves (11 b) remain open. Then the ball valve (3)is opened. The lance (7) is pushed inward against the flat or conicalseat (2 a). If the support tube (2) gets dirty, it can be rinsed outduring insertion of the lance (7) with the spraying liquid.

1-7. (canceled)
 8. In combination with a vessel at nonatmosphericpressure and with an elongated lance having an end provided with anozzle, a nozzle-changing system comprising: a support tube fixed to andopening into the vessel at a nozzle seat, the lance being fittable inthe tube in an inner position with the nozzle fitted to the seat; a mainvalve provided on the tube outward of the seat and displaceable betweena closed position and an open position; a plurality of seal rings spacedalong the tube outward of the valve and fittable with the lance in thetube to form respective annular compartments in the tube around thelance; and means including purge valves opening into the compartmentsfor admitting fluids into and draining fluids from the compartments. 9.The nozzle-changing system defined in claim 8 wherein the seal ringsinclude an outer seal ring, an intermediate seal ring between the outerring and the main valve and forming with the outer seal ring an outercompartment, and an inner seal ring between the intermediate ring andthe main valve and forming with the intermediate seal ring anintermediate compartment and with the main valve an inner compartment,the purge valves including respective outer, intermediate, and innervalves opening into the compartments.
 10. The nozzle-changing systemdefined in claim 9, further comprising means including a drain valveconnected underneath the intermediate compartment for draining fluidtherefrom.
 11. The nozzle-changing system defined in claim 9, furthercomprising supplies of the blocking fluid connected to the outer andintermediate purge valves.
 12. The nozzle-changing system defined inclaim 8, further comprising a guide in the tube aligned with the seatand engageable with the lance for coaxial alignment of the lance in thetube and nozzle in the seat.
 13. The nozzle-changing system defined inclaim 8 wherein the seat is flat.
 14. The nozzle-changing system definedin claim 8 wherein the seat is tapered and centered on an axis of thetube.